Much of the English language’s notorious complexity can be attributed to its verbal structure, which is only partially rule governed; there are plenty of rules but also plenty of exceptions. Every verb in the English language has five distinct properties: mood, voice, tense, person and number. And there are three separate kinds of mood: indicative, imperative and subjunctive. Dr. L. Kip Wheeler, a professor at Carson-Newman College in Tennessee, states that verb moods "indicate a state of being or reality."

Understanding the Basic Concept of Mood

Verbs are understood as action words but they can be more complex.
Verbs are understood as action words but they can be more complex.

The term “verb” is frustratingly broad all on its own; it can cover any word that captures an action, occurrence or state of being. It’s common to think of verbs as action words, or words that describe some kind of perceptible movement. Problematically, verbs can also denote mental and emotional states. The mood of a verb designates the manner in which it expresses the action it references. More specifically, a verb’s mood tells the reader if it is used to articulate a factual condition, issue a command or express a doubt or wish. According to the “Chicago Manual of Style,” these three functions correspond to the three kinds of mood: indicative, imperative and subjunctive.

The Indicative Mood

The indicative mood describes or interrogates a simple, factual condition.
The indicative mood describes or interrogates a simple, factual condition.

The indicative mood is the clearest of the three types since it is only used to describe or question a factual condition. For example: “Suzy ate the last piece of bread.” This a simple declaration of fact that uses a verb (ate) to describe an action. Another example: “Did Suzy eat the last piece of bread?” In this case, a question is being raised about a factual state of affairs.

The Imperative Mood

The imperative mood is used to issue a command.
The imperative mood is used to issue a command.

The imperative mood is used to issue a command or request of some kind. For example: “Put that knife down!” It’s important to note that the imperative mood is often used to communicate a sentence that has the formal structure of a command but isn’t intended to compel any particular action. Consider this farewell: “Call me later.” Even if this isn’t literally intended as an order, it still counts as an instance of the imperative mood. As the “Chicago Manual of Style” notes, a use of the imperative mood “usually has an understood 'you' as the sentence’s subject.”

The Subjunctive Mood

The subjunctive mood can be used to express a wish or desire.
The subjunctive mood can be used to express a wish or desire.

The subjunctive mood is the most complex of the three types since, instead of depicting a factual condition, it describes an action that is only imagined, conceived or wished for. For example, it is used to communicate wishful thinking: “I wish I could quit my job.” Or it can be used to express a hypothetical situation: “If I were faster, I would become a track star." The subjunctive mood can also be used to dispense an indirect suggestion or request: “You should finish your homework.”